JPH0989970A - Deteriorated state detecting device for resistive junction electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the deteriorated state of a resistive junction electrode resulted from the fixation of a plating material such as solder by detecting the peak voltage generated between resistive joined electrodes, and judging the deterioration on the basis of this peak voltage. SOLUTION: The voltage generated between resistive junction electrodes 24, 26 is sampled every prescribed time. The peak voltage Vpi in the process of resistive junction is compared with a preset peak voltage maximum value determined as a threshold Vh, and when Vpi>Vh is not established, it is judged that no abnormal peak voltage Vpi is generated in welding. When Vpi>Vh is established, it shows the generation of abnormal Vpi, and processing for measuring the frequency of Vpi detection and adding the Vpi exceeding the threshold to determine an accumulated sum Vt is performed. In case of Cn>Ch where Cn showing the frequency of Vpi detection exceeding Vh exceeds a threshold Ch, it is judged that the electrodes 24, 26 are already deteriorated and needed to maintain. When Cn>Ch is not established, it is judged that no maintenance is needed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deterioration state detecting device for a resistance-bonding electrode, and more particularly, to a deterioration state for detecting a deterioration state of a resistance-bonding electrode used for resistance-bonding an object plated with solder or the like. Regarding a detection device.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 60-2053.
As disclosed in Japanese Patent Laid-Open No. 45-45, there is known a device that detects deterioration of electrodes based on a change in interelectrode resistance. Deterioration of the electrode occurs because the shape, characteristics, etc. of the electrode change with time as the electrode is used. These changes often accompany changes in electrical resistance, and in some cases the deterioration state of the electrodes can be detected based on the changes in resistance.

The device described in the above publication is a device configured to detect deterioration of a glass electrode used in a pH meter. The change in the interelectrode resistance is detected based on the change in the voltage drop (effective value) generated between the electrodes when an alternating current of a predetermined flow rate is supplied between the glass electrodes. Since the resistance of the glass film of the glass electrode used in the pH meter changes with deterioration, such a device can appropriately detect the deterioration state of the glass electrode.

By the way, in the field of manufacturing electronic parts and the like, as a method of joining terminals and the like, a joining method utilizing resistance heating generated when an electric current is applied to an article to be joined, that is, a resistance joining is known. . The resistance bonding is performed by sandwiching two objects to be bonded, which are in contact with each other, between the resistance bonding electrodes, and further flowing a predetermined amount of current between the resistance bonding electrodes. Since a relatively large electric resistance is generated near the interface between the two objects to be bonded, when a current flows as described above, a relatively large resistance heat is generated near the interface between the objects to be bonded, and the interfaces are bonded. .

In carrying out the resistance bonding, it is necessary to control the effective voltage applied between the resistance bonding electrodes, the effective current flowing between the resistance bonding electrodes, etc. as management items. Therefore, the resistance junction device is provided with a mechanism for detecting and controlling the effective voltage and the effective current. Therefore, it is extremely convenient if the deterioration of the resistance junction electrode can be judged based on the effective voltage generated between the electrodes, like the glass electrode of the pH meter described above.

[0006]

In the field of manufacturing electronic parts, as a deterioration mode of a resistance-bonding electrode, a plating material is applied to the surface of the resistance-bonding electrode such as Sn (tin) or solder on the surface of the object to be welded. There is a known mode in which is stuck. Such deterioration occurs due to the following reasons.

That is, in the field of manufacturing electronic parts, Cu
A highly conductive material such as (copper) is used as an article to be joined. Therefore, it is difficult to secure a sufficient heat generation amount due to resistance heat generation simply by passing an electric current through the object to be welded. In such a case, for the purpose of assisting heat generation during energization, the surface of the object to be bonded is subjected to solder plating having a relatively low conductivity, and the conductivity is relatively low and the specific resistance value is low. High W (tungsten) and Mo (molybdenum)
Etc. are used as the material of the resistance junction electrode.
When such measures are taken, heat is generated not only on the object to be bonded but also on the resistance-bonding electrode itself and the surface of the object to be bonded during energization, and the amount of heat required for resistance bonding can be relatively easily secured. . However, if the resistance bonding electrode itself generates heat and reaches a high temperature under the condition that the surface of the object to be bonded is plated with solder or the like having a low melting point, the plating material may melt and adhere to the resistance bonding electrode. And then
When the resistance-joining electrode is cooled, a plating material such as solder adheres to the surface of the resistance-joining electrode, causing the above-described deterioration.

When the plating material such as solder adheres to the surface of the resistance-bonding electrode as described above, the contact state between the resistance-bonding electrode and the object to be welded becomes unstable, and it becomes difficult to secure stable bonding quality. Therefore, when the resistance junction electrode is deteriorated, it is necessary to detect the deterioration and rapidly polish the resistance junction electrode.

However, in the mode in which the plating material such as solder adheres to the surface of the resistance-bonding electrode, the electric resistance of the resistance-bonding electrode itself does not change so much. Further, when the plating material adhered to the surface of the resistance-bonding electrode is melted during the resistance-bonding process, the contact state between the resistance-bonding electrode and the object to be joined becomes substantially the same as the state before deterioration. Therefore, it is difficult to accurately determine the deterioration state of the resistance junction electrode based on the effective voltage generated between the resistance junction electrodes. In this sense, the method of determining the deterioration state of the electrode based on the effective voltage generated between the electrodes as disclosed in the above publication is not necessarily appropriate as the method of determining the deterioration state of the resistance-junction electrode.

The present invention has been made in view of the above points, and a deterioration state of a resistance-joining electrode due to adhesion of a plating material such as solder is converted into a peak voltage generated between electrodes during the resistance-joining process. An object of the present invention is to provide a device for detecting a deterioration state of a resistance junction electrode, which is determined based on the above.

[0011]

The above-mentioned object is defined in claim 1.
And a peak voltage detecting means for detecting a peak voltage generated between the resistance junction electrodes in the process of resistance junction,
And a deterioration state detection unit that detects a deterioration state of the resistance junction electrode based on the peak voltage.

In the present invention, the peak voltage detecting means detects the peak voltage generated between the resistance junction electrodes during the resistance junction process. For example, when the surface of the resistance-joining electrode is roughened because the plating applied to the surface of the object-to-be-joined adheres to the resistance-joining electrode, the contact state between the resistance-joining electrode and the object to be joined becomes unstable, A situation occurs in which the two cannot come into surface contact. In a situation where the resistance-bonding electrode and the object to be bonded do not come into surface contact with each other, the electric current is concentrated at the contact point between them, so that the electrical resistance at the interface between the resistance-bonding electrode and the object to be bonded increases. Under such a situation, a large voltage is temporarily generated between the resistance junction electrodes after the resistance junction is started. In this respect, the peak voltage generated between the resistance junction electrodes accurately represents the deteriorated state of the resistance junction electrodes. Therefore, the detection result of the deterioration state detecting means accurately represents the deterioration state of the resistance junction electrode.

Further, as described in claim 2, the above-mentioned object is, in the deterioration state detecting device of the resistance junction electrode according to claim 1, the deterioration state detecting means for each of a plurality of resistance welding processes. The present invention can also be achieved by a deterioration state detecting device for a resistance junction electrode, which detects the deterioration state of the resistance junction electrode based on the cumulative sum of the detected peak voltages.

In the present invention, the deterioration state detecting means accumulates the peak voltage between the resistance junction electrodes generated in a plurality of resistance junction processes, and detects the deterioration state of the resistance junction electrode based on the cumulative sum. Since each peak voltage reflects the deterioration state of the resistance junction electrode, the cumulative sum of the peak voltages remarkably reflects the deterioration state of the resistance junction electrode.
Therefore, when the deterioration state of the resistance junction electrode is judged based on the cumulative sum of the peak voltages as in the present invention, the deterioration state of the resistance junction electrode can be detected more accurately.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an overall configuration diagram of a resistance junction system which is an embodiment of the present invention. In FIG.
The R terminal, S terminal, and T terminal are terminals connected to the R, S, and T phases of the three-phase AC power supply, respectively. Diodes 10a and 12a are respectively connected to the R terminal, the S terminal, and the T terminal.
14a anode terminal and the diode 10b; 12b;
The cathode terminal of 14b is connected. These diodes 10a, 10b; 12a, 12b; 14a, 1
Reference numeral 4b constitutes a full-wave rectification circuit for R, S, and T phases, respectively.

The cathode terminals of the diodes 10a; 12a; 14a are connected to the high voltage line 16 of the resistance junction device. The anode terminals of the diodes 10b; 12b; 14b are connected to the low voltage line 18 of the resistance junction device. A capacitor 19 having a sufficiently large capacity is connected between the high voltage line 16 and the low voltage line 18 in order to stabilize the voltage. Therefore, the high pressure line 1
The voltage between 6 and the low voltage line 18 is maintained substantially constant.

An H bridge circuit 20 composed of four switching elements 20a to 20d is connected between the high voltage line 16 and the low voltage line 18. The four switching elements 20a to 20d allow the flow of current from the high-voltage line 16 to the low-voltage line 18, respectively, and the switching elements 20a and 20d are diagonal and the switching elements 20b and 20d are diagonal. It is arranged to be located.

One end of the primary coil 22a of the inverter transformer 22 is connected to each of the path connecting the switching elements 20a and 20b and the path connecting the switching elements 20c and 20d. The anode terminal of the diode 22c or 22d is connected to each end of the secondary coil 22b of the inverter transformer 22, and the center tap 22e is connected to the center of the secondary coil 22b.

The resistance bonding apparatus of this embodiment is provided with a pair of resistance bonding electrodes 24 and 26. Resistance junction electrodes 24, 2
6 is held by one of the pressurizing cylinders 28 and 30 so as to be displaceable in the axial direction. The diodes 22c and 22d of the above-described inverter transformer 22 are both connected to one resistance junction electrode 24 at the cathode terminal. Further, the center tap 22e of the inverter transformer 22 is connected to the other resistance junction electrode 26. The pressurizing cylinders 28 and 30 are CPUs described later.
In accordance with the command of 32, the object to be bonded is connected to the resistance bonding electrode 24,
It can be moved to a position separated from 26 (hereinafter referred to as an open end) and a position in contact with the resistance-bonding electrodes 24 and 26 (hereinafter referred to as a pressure end).

The operation of the joining device of this embodiment is controlled by the CPU 32. As shown in FIG. 1, the CPU 32 includes a power supply circuit 34, a primary current detection circuit 36, an inverter drive circuit 38, a secondary current detection circuit 40, an inter-chip voltage detection circuit 42, a memory 44, an input section 46, a display section 48,
And the monitoring device 50 is connected.

The power supply circuit 34 is a circuit for supplying drive power to the CPU 32, and uses the commercial AC supplied from the above-mentioned S terminal and T terminal to generate a predetermined DC voltage necessary for controlling the joining apparatus. The primary current detection circuit 36 is a circuit that detects a current flowing through the high voltage line 16, that is, a current flowing through the primary coil 22a of the inverter transformer 22. As shown in FIG. 1, the high voltage line 16 is provided with a current detector, for example, a Hall CT 36a, which outputs an output according to the value of a current passing through the high voltage line 16. The primary current detection circuit 36 detects the current flowing through the high voltage line 16 based on the output signal of the Hall CT 36a.

The inverter drive circuit 38 is a circuit for switching the on / off state of the switching elements 20a to 20d in response to a command from the CPU 32. The inverter drive circuit 38 is configured so that the pair of switching elements 20a, 20d or 20b, 20c located diagonally to each other are turned on at the same time, and the on state is alternately changed at the frequency instructed. And the switching element 20a
Drive ~ 20d. When such control is performed, the voltage applied across the primary coil 22a of the inverter transformer 22 is inverted at the frequency commanded by the CPU 32.

When the voltage applied to the primary coil 22a is reversed as described above, the secondary coil 22b is excited with an AC voltage corresponding to its frequency. When an AC voltage is excited in the secondary coil 22b, a potential equal to or higher than the potential of the center tap 22e is generated at one end of the secondary coil 22b, and a potential equal to or lower than the potential of the center tap 22e is generated at the other end. Then, in the present embodiment, among the potentials generated at both ends of the secondary coil 22b, a potential equal to or higher than the potential of the center tap 22e is supplied to one resistance junction electrode 24, and the potential of the center tap 22e is equal to that of the other. It is supplied to the resistance junction electrode 26. Therefore, the DC voltage of the positive electrode on the side of the resistance bonding electrode 24 and the negative electrode on the side of the resistance bonding electrode 26 is always applied between the resistance bonding electrodes 24 and 26. In this embodiment, the frequency of 1 kHz to 4 kHz can be set as the practical frequency.

Resistance junction electrode 24 and inverter transformer 2
The toroidal coil 40a is arranged in the path communicating with the secondary coil of No. 2. Toroidal coil 40a
Is a coil that outputs a signal corresponding to the magnitude of an alternating current flowing through the inside thereof, and its output terminal is connected to the secondary current detection circuit 40. Secondary current detection circuit 4
0 detects the instantaneous value of the current supplied to the resistance junction electrode 24 based on the output of the toroidal coil 40a, and supplies the detected value to the CPU 32. The CPU 32 calculates the effective value of the current based on the instantaneous value of the current supplied from the secondary current detection circuit 40.

Two probe terminals provided in the inter-chip voltage detection circuit 42 are connected to the resistance junction electrodes 24 and 26, respectively. The inter-chip voltage detection circuit 42 uses the resistance junction electrodes 24 and 26 input from these probe terminals.
The voltage generated between the two is detected based on the electric potential of, and the detected value is supplied to the CPU 32. The CPU 32 calculates the effective voltage generated between the resistance-junction electrodes 24 and 26 based on the detection value of the inter-chip voltage detection circuit 42.

In carrying out the resistance joining, it is necessary to set conditions such as the duration of the joining current and the magnitude of the joining current according to the object to be joined. In the system of this embodiment, these conditions are set via the input unit 46. Since it is necessary to manage the energy supplied from the resistance-bonding electrodes 24 and 26 to the object to be bonded in the resistance bonding, the condition input and the control by the CPU 32 use the actual values of the current and the voltage. It may be done.

The system according to the present embodiment has a resistance junction electrode 2
It is characterized in that the monitoring device 50 is connected to 4, 26. The monitoring device 50 is a device that detects the deterioration state of the resistance-bonding electrodes 24 and 26 based on the peak voltage that acts between the resistance-bonding electrodes 24 and 26 during the resistance-bonding process, and has the configuration shown in FIG. ing.

FIG. 2 shows a monitoring device 5 which is an essential part of this embodiment.
FIG. As shown in the figure, the monitoring device 50 is a device mainly composed of the CPU 50a. The inter-electrode voltage detection circuit 50b, the input unit 50c, the display unit 50d, the I / O port 50e, and the memory 50f are connected to the CPU 50a.

The current-to-current voltage detection circuit 50b is connected to the resistance-bonding electrodes 24 and 26, respectively.
The voltage across 26 is detected. The inter-electrode voltage detection circuit 50
It is also possible to substitute the above-mentioned inter-chip voltage detection circuit 42 for b. The input unit 50c is a device for inputting various thresholds when performing deterioration detection based on the peak voltage. In the present embodiment, the resistance junction electrode 2
4,26 to determine whether degradation has occurred, the upper limit value V _H, the peak voltage V _Pi that exceeds the V _H peak voltage V _Pi generated across resistor junction electrodes 24 and 26 in the resistor junction is detected Three of the upper limit value C _H of the number of times C _{M and} the upper limit value V _ACC of the cumulative sum of the peak voltage V _Pi exceeding V _H are used as threshold values. Therefore, in the present embodiment, the three threshold values V _H , C _H , and V _ACC described above are input from the input unit 50c.

The display unit 50d is a device for displaying various threshold values input as described above. The memory 50f is
It is a memory that stores information necessary for the CPU 50a to execute a predetermined process. Also, I / O port 50e
Is the CPU 50a shown in FIG. 2 and the CPU shown in FIG.
32, and an interface for connecting to an external device such as an alarm device. A start signal and an end signal are input to the CPU 50a via the I / O port 50e, while the alarm signal generated by the CPU 50a is supplied to the alarm device via the I / O port 50.

FIG. 3 shows a time chart for explaining the operation of the system of this embodiment. FIG. 3 (A) is shown in FIG.
The ON / OFF state of the electrode pressing signal output from the CPU 32 to the pressing cylinders 28 and 30 shown in FIG. The change shown in the figure shows a state in which the electrode pressurizing signal is switched from OFF to ON at time t ₀ with the activation of the bonding apparatus.

FIG. 3B shows a change state in which the pressure cylinder moves from the open end to the pressure end in response to the electrode pressure signal. The change shown in the figure is that at time t ₀ , the pressure cylinder 2
The displacements of 8 and 30 are started, and they reach the pressurizing end at time t ₁ . FIG. 3C shows the resistance-joining electrode 2
4 shows the on / off state of the junction current flowing through Nos. 4 and 26. As shown in the figure, the joining current starts to be supplied when a predetermined time elapses after the pressurizing cylinders 28, 30 reach the pressurizing end. After that, the junction current is turned off again at time t ₃ after a preset predetermined period has elapsed.

FIG. 3D shows an operating state of the inter-electrode voltage detection circuit 50b of the monitoring device 50. As shown in the figure, the inter-electrode voltage detection circuit 50b starts detecting the inter-electrode voltage at the same time when the junction current is turned on, and continues the detection until the junction current is turned off.

As described above, when the junction current is turned off at time t ₃ and the operation of the inter-electrode voltage detection circuit 50b is stopped,
After that, at time t ₄ , the electrode pressing signal is turned off to move the pressing cylinders 28 and 30 to the open ends (FIG. 3).
(A)). Then, the movement of the pressure cylinders 28 and 30 is started following the change of the electrode pressure signal, and the series of joining steps is ended at time t ₅ (FIG. 3 (B)). C shown in FIG.
The PU 32 and the CPU 50a shown in FIG. 2 perform a predetermined process so that each unit operates at the above timing after the joining device is activated.

By the way, in the system of this embodiment, the deterioration state of the resistance-bonding electrodes 24, 26 is detected based on the peak voltage generated between the resistance-bonding electrodes 24, 26 during the resistance-bonding process. Hereinafter, the reason why the deterioration state of the resistance junction electrodes 24 and 26 can be accurately grasped based on the peak voltage will be described.

FIG. 4 is an enlarged view of the resistance-bonding electrodes 24 and 26 and the two objects to be bonded 52 and 54 sandwiched between the resistance-bonding electrodes 24 and 26 in a state of being in contact with each other. The objects to be joined 52 and 54 are members made of a highly conductive material such as Cu (copper), and the surfaces thereof are plated with Sn (tin) or solder.

When the objects to be joined 52, 54 are made of a highly conductive material such as Cu, the resistance heat generated when a current flows through them is relatively small. Therefore, under such a circumstance, by simply passing a current through the objects to be joined 52, 54,
It is difficult to obtain a sufficient amount of heat for joining the interfaces of the objects to be joined 52, 54.

Therefore, in this embodiment, the objects to be joined 52 and 54 are plated as described above, and the resistance-joining electrodes 24 and 26 are made of W (tungsten) or Mo (molybdenum) having a relatively low conductivity. It consists of. When the objects to be joined 52, 54 are plated, a relatively large amount of resistance heat is generated when a current flows through the plated parts. Further, when the resistance-joining electrodes 24 and 26 are made of W, Mo, or the like, the resistance-joining electrodes 24 and 2 are connected during resistance-joining.
6 itself can generate heat to assist the overheating of the objects to be joined 52, 54. Therefore, according to the system of this embodiment,
Although the objects to be joined 52 and 54 have high conductivity, good joining quality can be obtained by resistance joining.

By the way, as described above, the objects to be joined 52, 5
The surface of 4 is plated with Sn or solder with a low melting point,
In addition, under the condition that the resistance bonding electrodes 24, 26 themselves become high in temperature, the plating on the surfaces of the objects to be bonded 52, 54 is melted during the resistance bonding process, and the plating material adheres to the resistance bonding electrodes 24, 26. Can happen. Then, when the resistance bonding electrodes 24 and 26 are cooled after the plating is attached, a state in which the plating material is fixed to the surfaces of the resistance bonding electrodes 24 and 26 is formed.

FIG. 5 shows the resistance-bonding electrode 26 having a plating material adhered to the surface thereof and the object 54 to be bonded due to the above-mentioned phenomenon.
The enlarged view of the contact part with is shown. When the plating material adheres to the surface, as shown in FIG. 5, the surface of the resistance bonding electrode 26 (and the resistance bonding electrode 24) is roughened. In this case, the contact state between the object to be bonded 54 and the resistance bonding electrode 26 is point contact at a plurality of points. When energization of the joining current is started in such a contact state, the joining current is concentrated on the point where the resistance joining electrode 26 and the article to be joined 54 are in contact with each other, and good joining quality is maintained over the entire joining portion. Will be difficult.

As described above, when the junction current is concentrated and locally distributed, the electric current at the interface between the resistance junction electrode 26 and the object to be welded 54 is higher than that when the junction current flows uniformly over the entire resistance junction electrode 26. Resistance increases. Therefore, under such a situation, a higher resistance junction electrode voltage is generated when the junction current is applied, as compared with the case where the resistance junction electrode 26 and the article 54 to be joined are in surface contact with each other.

However, in the process of resistance bonding, the resistance bonding electrodes 24, 26 and the objects to be bonded 52, 54 are heated as the conduction of the bonding current is continued, and eventually the resistance bonding electrodes 24, 26 are heated. The plating material adhered to the surface is melted, and the contact state between the resistance-joining electrodes 24 and 26 and the objects to be joined 52 and 54 shifts to surface contact. Therefore, the resistance junction electrodes 24, 26
If the plating material adheres to the surface of the
It is only in the initial stage of resistance bonding that the voltage between the resistance bonding electrodes is higher than that in the case where the plating material is not fixed to the surfaces of 4, 26. For this reason, the resistance junction electrodes 24,
It is difficult to detect the deterioration state of No. 6.

On the other hand, the resistance-bonding electrode 2 in the case where the plating material is fixed to the resistance-bonding electrodes 24 and 26
The peak voltage between 4 and 26 is always the resistance junction electrodes 24 and 2.
This occurs when 6 and the objects to be joined 52, 54 are in a point contact state. Therefore, in the process of resistance bonding, the resistance bonding electrode 2
The peak voltage generated between Nos. 4 and 26 accurately represents the deteriorated state of the resistance junction electrodes 24 and 26.

The above conclusions can also be derived from the experimental data shown in FIGS. 6 to 9. That is, FIG. 6 shows that the resistance-bonding electrodes 24 and 26 having no plating material adhered to the surface thereof.
A change state of the voltage between the resistance-junction electrodes when resistance-joining is performed using (hereinafter referred to as a new electrode) is shown. The peak voltage in the figure is 1.12V. On the other hand, FIG. 7 shows a change state of the voltage between the resistance-joining electrodes when resistance-joining is performed using the resistance-joining electrodes 24 and 26 (hereinafter referred to as deteriorated electrodes) having the plating material adhered to the surfaces thereof. The peak voltage shown in the figure is 1.44V. As described above, in the experimental examples shown in FIGS. 6 and 7, a difference of 0.32 V is recognized in the peak voltage between the case where the new electrode is used and the case where the deteriorated electrode is used. When the voltage between the resistance-junction electrodes shown in FIGS. 6 and 7 is expressed as an effective value, 0.82 V in FIG. 6 and 0.86 V in FIG.
V. In this case, since the difference between the two is only 0.04 V, it is difficult to clearly identify the two.

FIG. 8 shows the results of the peak voltage between the resistance-junction electrodes 24 and 26 detected for each resistance junction expressed in a histogram, which is obtained by performing resistance junction 500 times using a new electrode. The average value of all data shown in the figure is 1.20.
V, the variance σ of all data is 0.066. On the other hand, FIG.
Is a histogram of the peak voltage between the resistance-welding electrodes 24 and 26 detected for each resistance-joining when the resistance-joining is performed 500 times using the deteriorated electrode that has already been used for resistance-welding 2500 times. The results shown are shown. The average value of all data shown in the figure is 1.35 V, and the variance σ of all data is 0.2.
It is 08. As described above, when the resistance junction electrodes 24 and 26 are deteriorated, the high peak voltage is detected more frequently, and the variation range of the peak voltage becomes wider.

As described above, the peak voltage generated between the resistance-bonding electrodes 24 and 26 during the resistance-bonding process accurately represents the deteriorated state of the resistance-bonding electrodes 24 and 26. Therefore,
As in the system of this embodiment, the resistance-bonding electrodes 24, 26 are based on the peak voltage generated between the resistance-bonding electrodes 24, 26.
If the deterioration state is judged, the deterioration state can be detected with high accuracy. In the system of the present embodiment, the deterioration state of the resistance junction electrodes 24 and 26 is monitored, and the deterioration is
An alarm will be issued when the process progresses to the extent that it becomes difficult to maintain stable joining quality.

The contents of the processing executed by the CPU 50a to realize the above functions will be described below with reference to FIGS. 10 and 11. 10 and 11 show a flowchart of an example of a control routine executed by the CPU 50a in this embodiment. This routine is executed at the timing when the resistance joining device is activated and the conduction of the joining current is started.

When this routine is started, first, at step 100, the voltage V _Ai generated between the resistance-junction electrodes 24 and 26 is set every predetermined time (every 0.5 msec in this embodiment).
The process of sampling is executed. The processing of this step is continued while the junction current is flowing, and the CPU
The process ends when a command to turn off the junction current is issued from 32.

When the process of step 100 is completed, next, at step 102, the maximum value of the inter-electrode voltage V _Ai generated in the current resistance welding process, that is, the peak voltage V _Pi in the current resistance welding process is obtained. To be Once V _Pi is obtained, it is then determined in step 104 whether V _Pi > V _H holds. V _H is a threshold value input as the upper limit value V _H of the peak voltage V _Pi generated between the resistance junction electrodes 24 and 26 as described above. Therefore, V _Pi
When> V _H is not established, it can be determined that the abnormal peak voltage V _Pi did not occur during the resistance welding this time. In this case, the routine of this time is ended thereafter without executing any special processing. On the other hand, V _Pi ＞
When V _H is satisfied, it means that an abnormal peak voltage V _Pi is generated during the current resistance welding. In this case, the process of step 106 is executed thereafter.

At step 106, a counter C _M for counting the number of times V _Pi exceeding V _H is detected is incremented. C _M is a counter that is reset to “0” when the resistance-joining electrodes 24 and 26 are replaced with new ones or polished. Therefore, the value of the counter C _M represents the number of times that V _Pi exceeding V _H is detected by the resistance contact electrodes 24 and 26 currently used.

After the above processing is completed, the next step 10
Then, the process proceeds to step S8, in which V _Pi detected this time is added to the cumulative sum V _T of V _Pi exceeding V _H. V _T is reset to “0” when the resistance junction electrodes 24 and 26 are replaced or polished. Therefore, the value of the cumulative sum V _T is
It represents the cumulative sum of V _Pi over V _H generated by the currently used resistive junction electrodes 24, 26.

After the processing of step 108 is completed,
At step 110, the counter C _MIs the threshold C_H
Is determined. Threshold C_HIs on
As I said, V_HVoltage V exceeding_PiWhen is detected
Number C_MIs an upper limit value for. More specifically, contacted
Management to maintain the joint state of compound 52, 54 properly
The value is a value that is determined based on actual results and the like.

Therefore, when C _M > C _H is established, it can be determined that the resistance-joining electrodes 24 and 26 have already deteriorated and that maintenance is required. In this case, thereafter, in step 112, after the alarm output 1 is output, the process of step 114 is executed. on the other hand,
If C _M > C _H still does not hold, the resistance junction electrode 2
It can be determined that maintenance of 4, 26 is not yet necessary. In this case, step 112 is jumped to and the processing of step 114 is executed after step 110.

At step 114, it is judged if the cumulative sum V _T of the peak voltage V _Pi exceeding V _H exceeds the threshold value V _ACC . The threshold V _ACC is, as described above,
It is a value set as the upper limit value of the cumulative sum V _T of V _Pi .
More specifically, similar to C _H described above, the objects to be bonded 52,
As a control value for properly maintaining the joining state of 54,
It is a value determined based on actual results.

Therefore, when V _T > V _ACC holds,
It can be determined that the resistance-joining electrodes 24 and 26 have already deteriorated and require maintenance. In this case, after the alarm output 2 is output in step 116, the process proceeds to step 118 shown in FIG. on the other hand,
If V _T > V _ACC still does not hold, it can be determined that the maintenance of the resistance junction electrodes 24 and 26 is not yet necessary. In this case, step 116 is jumped to and the processing of step 118 is executed after step 114.

In step 118, it is judged whether or not the operator using the system of this embodiment has performed an operation to reset the counter C _M. The condition of this step is determined to be unsatisfied when the alarm output 1 is not output, and when the operator does not take a measure for the alarm after the alarm output 1 is output. In such a case, steps 120 to 124 are jumped, and then the process of step 126 is executed.

In step 126, it is judged whether or not the operator who uses the system of this embodiment has performed an operation of resetting the cumulative sum V _T. The condition of this step is determined to be unsatisfied when the alarm output 2 is not output and when the operator has not taken any action for the alarm after the alarm output 2 is output. In such a case, steps 128 to 132 are jumped,
Then, the process of step 134 is executed.

At step 134, it is judged if any warning is output. As a result, when it is determined that no alarm is output, the routine of this time is ended, and thereafter, each time the resistance bonding device is activated,
The processing from step 100 onward is repeatedly executed. On the other hand, if it is determined that any of the alarms is output, the processing from step 118 onward is executed again.

When it is determined in the above step 110 that C _M > C _H is satisfied, and the operator resets the counter C _M after the alarm output 1 is output in step 112, the condition of step 118 is satisfied. After that, the process of step 120 is executed.

At step 120, it is judged if the alarm output 1 is output. As a result, if the alarm output 1 is still output, after the output of the alarm output 1 is stopped in step 122, the process of resetting the counter C _{M in} step 124 is executed. On the other hand, when it is determined in step 120 that the alarm output 1 has not been output, step 122 is jumped, and the process of step 124 is directly executed after step 120.

In step 114, V _T >
After it is determined that V _ACC is established and the alarm output 2 is output in step 112, the cumulative sum V _{T is set} by the operator.
When the operation of resetting is performed, the condition of step 126 is satisfied, and thereafter the process of step 128 is executed.

At step 128, it is judged if the alarm output 2 is output. As a result, when the alarm output 2 is still output, after the output of the alarm output 2 is stopped in step 130, the process of resetting the cumulative sum V _T is executed in step 132. On the other hand, if it is determined in step 128 that the alarm output 2 has not been output, step 130 is skipped, and the process of step 130 is directly executed after step 128.

According to the above process, the resistance junction electrodes 24,
After the 26 is replaced with a new one, the resistance junction electrodes 24 and 26 are deteriorated, and a peak voltage exceeding the threshold V _H is frequently detected exceeding the allowable range for obtaining stable junction quality. Then, the alarm output 1 or the alarm output 2
Is output. Then, the alarm is continuously output until the operator performs a reset operation.

Therefore, according to the system of this embodiment,
The need for maintenance of the resistance joint electrodes 24 and 26 can be appropriately displayed to the operator. still,
Since the electrodes such as W and Mo have sufficient hardness as compared with the plating material such as solder, if the deterioration state can be detected, the resistance-joining electrodes 24 and 26 can be properly placed by polishing or the like. It is relatively easy to maintain. In this respect, the system of the present embodiment has an advantage that the resistance junction electrodes 24 and 26 can be maintained in a good state easily and reliably.

By the way, in the above embodiment, it is determined whether or not to output the alarm output 2 based on whether or not the cumulative sum V _T exceeds a predetermined threshold value V _ACC. The invention is not limited to this, and for example, the cumulative sum V _T may be divided by the number of times of resistance junction execution to calculate the average peak voltage, and the same determination may be performed using that value.

In the above embodiment, the CPU 50
a executes the processing of steps 100 and 102, the peak voltage detecting means performs the processing of steps 104 to 116, and the deterioration state detecting means according to claim 1 particularly, By executing the processing of steps 108, 114 and 116, the deterioration state detecting means according to claim 2 is realized.

By the way, in the above embodiment, C _M
Exceeds a predetermined value C _H , and V _T is a predetermined value V
_{Although the} electrode deterioration is determined when _ACC is exceeded, the electrode deterioration may be determined when V _T × C _M exceeds a predetermined value. Also, in the above example,
Although the configuration in which the monitoring device 50 is provided separately from the control device of the resistance junction device has been described, the CPU 50a of the monitoring device 50, the inter-electrode voltage detection circuit 50b, the input unit 50c, the I / O port 50.
e, the memory 50f is the CPU 3 of the control device of the resistance junction device
2, the inter-electrode voltage detection circuit 42, the input unit 46, the I / O port 49, and the memory 44 can be used instead.

[0068]

As described above, according to the first aspect of the invention, the deterioration state of the resistance junction electrode is detected based on the peak voltage generated between the resistance junction electrodes during the resistance junction process.
Here, the peak voltage generated between the resistance junction electrodes corresponds to the deteriorated state of the resistance junction electrodes accurately. For this reason,
According to the deterioration state detection device of the resistance junction electrode of the present invention, the deterioration state of the resistance junction electrode can be detected with high accuracy.

According to the second aspect of the present invention, the deterioration state of the resistance-junction electrode is detected based on the cumulative sum of the peak voltages between the resistance-junction electrodes generated in the plurality of resistance-joining processes. The cumulative sum of the peak voltages remarkably reflects the deterioration state of the resistance junction electrode. Therefore, according to the deterioration state detecting device of the resistance-junction electrode of the present invention, the deterioration state of the resistance-junction electrode can be detected more accurately as compared with the invention described in claim 1.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a monitoring device that is a main part of one embodiment of the present invention.

FIG. 3 is a time chart for explaining the operation of the system according to the exemplary embodiment of the present invention.

FIG. 4 is an enlarged view of a resistance-junction electrode according to an embodiment of the present invention.

FIG. 5 is an enlarged view of the resistance-junction electrode of one embodiment of the present invention in a deteriorated state.

FIG. 6 is a diagram showing a change state of an inter-electrode voltage when a new electrode is used.

FIG. 7 is a diagram showing a change state of an inter-electrode voltage when a deteriorated electrode is used.

FIG. 8 is a histogram of inter-electrode peak voltage when a new electrode is used.

FIG. 9 is a histogram of inter-electrode peak voltage when a deteriorated electrode is used.

FIG. 10 is a flowchart (part 1) of an example of a control routine executed in the embodiment of the present invention.

FIG. 11 is a flowchart (part 2) of an example of a control routine executed in the embodiment of the present invention.

[Explanation of symbols]

 24,26 Resistance-joining electrode 28,30 Pressurizing cylinder 50 Monitoring device 32 50a CPU 50b Electrode voltage detection circuit 52,54 Joined object

Front page continued (72) Inventor Hiroshi Kikuchi 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Koji Moro 3 95-3 Futatsuka, Noda-shi, Chiba Miyachi Technos Co., Ltd.

Claims (2)

[Claims] 1. A peak voltage detection means for detecting a peak voltage generated between resistance junction electrodes in a resistance junction process, and a deterioration state detection means for detecting a deterioration state of the resistance junction electrode based on the peak voltage. A deterioration state detection device for a resistance-junction electrode, comprising: 2. The deterioration state detecting device for a resistance junction electrode according to claim 1, wherein the deterioration state detecting means is based on a cumulative sum of the peak voltages detected in each of a plurality of resistance welding processes. A deterioration state detection device for a resistance junction electrode, which detects a deterioration state of a resistance junction electrode.